Responding to news late today of a credible terrorist threat on the 10th anniversary of the Sept. 11, 2001 attacks, Police Chief Charlie Beck said the threat does not include Los Angeles as a target.

"I have been briefed on information, and all of that information reveals no credible threats against the City of Los Angeles at this time," Beck said during an afternoon news conference.

Citing unnamed sources, Fox News reported late today that federal authorities believe they have discovered a credible threat targeting New York City or Washington, D.C.

A senior official reportedly described the threat to Fox News as "specific enough to elicit worry" but stressed that it is still unconfirmed.

"It feels more than aspirational," another official told the network.

Asked today if there was still no known credible threat related to the 9/11 anniversary, Homeland Security Secretary Janet Napolitano told reporters: "It is still the case that we don't have something that would reach that standard, but we still have lots of chatter out there. And we take every bit of that seriously and track it down. ... The date is important because it's 9/11. But as I said, in the intel world there's lots of chatter and we're taking it all seriously. Should there be something that rises to the level where I have to issue a threat advisory, we will issue a threat advisory."

Beck said there would be thousands of LAPD officers throughout the weekend "not only in a normal crime fighting capacity, but also to keep an eye on our critical infrastructure."

He said that included stationing LAPD officers at Los Angeles International Airport, which is typically policed by Los Angeles Airport Police officers, and the Port of Los Angeles, which also has its own police force.

"What has made us effective in preventing terrorism in Los Angeles is the way we work, and the way we work is as a team," Beck said. "If you see something as a member of the public that doesn't make sense to you, particularly on this anniversary of the most horrific attack to occur on American soil, say something."

Beck urged residents to call 877-A-THREAT with anything that looks out of the ordinary over the weekend.